Switch Off!

Switches and Energy

Switches and Energy
Most modern gadgets, such as kettles and toasters, switch off automatically - this is not only important to conserve energy, but is a safety precaution too. Heating appliances, such as cookers and irons, have thermostats fitted so that a selected
temperature can be maintained - an internal switch turns the heater on or off as required. Because most of our electricity is generated from sources of energy like coal which will run out, we must be aware of the need to save energy whenever possible. The two-way switch is important today, both as a safety device and as a means of conserving energy. If a light can be switched on or off from the top or the bottom of a staircase, not only is it safer at night, but light energy can be saved. Make your own two-way switch and discover how it works.
Switch Off!
 

Switch Off 01

   

Position drawing pins at either end of a board so that two plastic lids can just turn, like knobs, within them.

Switch Off 02

 



Align four pins as shown and connect them in pairs with two lengths of wire. Make a hole in the top of one plastic knob and insert the two wires connected to a bulb holder.

Switch Off 03

Connect one wire to a paperclip inserted through the lid, as shown, taking the other to the batteries.

Switch Off 04

Form a switch at the other lid in the same way, connecting the wire to the batteries. Plasticine will hold the wires in place.






WHY IT WORKS

two-way switch

A two-way switch makes it possible to turn a light on or off in two different places. In order for this to work an alternative pathway for the electricity must be built into the circuit. For the electricity to flow along the blue or red wires, both ends must be connected to the battery at the same time. If the bulb is switched off by moving the paperclip from blue to red at one end, then it can be turned back on by changing from blue to red at the other end.

Switch Off

Check that the paperclips can reach each of the two drawing pins connected to the wires. Rotate the plastic knob, and watch the bulb light up when contact is made. Either ‘knob’ when turned, will turn the light off or on.

Bright ideas

• A person in a wheelchair may need a light switch to be lower down. Design a two-way switch circuit to satisfy this need.
• Build a two-way switch circuit and incorporate it into a card model staircase. Remember that you must incorporate an alternative circuit so that each switch works in two directions. If you increase the distance between the two switches, does it have any effect on the light produced? Do you need an extra battery? Try shortening the distance. Are there any changes?
• Find out how many two-way switches there are in your home or school. Make a record of where they are. Why are they positioned as they are? Identify those places where a two-way switch is needed.